Process for the manufacture of incandescent-lamp bases.



No. 882,258. PATENTED MAR. 17, 1908. M. M. MERRITT.

PROCESS FOR THE MANUFACTURE OF INGANDESOBNT LAMP BASES.

PPPP IGATION FILED MAY 27.1907.

fig.1. I792? Ll/l'lizesses UNITED srnrnsgarnnr OFFICE.

MATTHEW M. MERRITT, OF MIDDLETON, MASSACHUSETTS, ASSIGNOR TO NATIONAL ELEC- TRIO LAMP COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF NEW JERSEY.

PROCESS FOR THE MANUFACTURE OF INCANDESCENT-LAMP BASES.

Specification of Letters Patent.

Patented March 17, 1908.

Original application filed Iebruary 11, 1907, Serial No. 356,666. Divided and this application filed Kay 27, 1907. Serial No. 375,829.

To all whom it may concern:

Be it known that I, MATTHEW M. MER- BITT a citizen of the United States, residing at Middleton, county of Essex, and State of Massachusetts, have invented an Improvement in Processes for the Manufacture of Incandescent-Lamp Bases, of which the following description, in connection with the accompanying drawings, is a specification, like letters on the drawings representing like parts.

My invention relates to incandescent lamps, and is more articularly concerned with a novel process or the manufacture of and particularly the bases thereof. application is a division of my rior application, Serial No. 356,666, filed ebruary 11, 1907.

My invention will be best understood by reference to the following description when taken in connection with the accompan ing illustration of one specific embodiment o the same.

In the drawings :Figure 1 shows in section a form of mold for molding a dummy or false base of fusible metal or other like material; Fig. 2 shows a like mold where a solid insulating button is employed for the ti of the dummy base; Fig. 3 shows a modified form of mold for casting the metal in the Y form of an outer shell; Fig. 4 shows the dummy base electro-plated with conductive material; Fig. 5 shows the shell of conductive material with the fusible metal removed; 6 shows the shell illustrated in Fig. .5 with an inserted end filling of insulating material; Fig. 7 shows the completed base with a strip of conducting materlal re- -moved from the sides of the insulating filling; Fig. 8 shows a completed base made with the aid of the false base shown in Fig. 2, and, F 9 shows a completed lamp having attached thereto a base of the type shown in F 8.

R erring to the drawings and to the embodiment which I have there shown for the illustration of my invention, the construction of the lamp base, in accordance with the principles herein described, com rehends enerally the production of a shel of conducting materlal by the electrolytical depositing of metal upon a core or body of suitably formed filling material, which latter may afterwards be removed, as by fusion,

such filling material, by way of example, being of ordinary fusible metal fusin at a low temperature,or some of the Earder waxes, such as paraffin. Such procedure leaves a shell of copper, or such other conducting metal as may be employed, and this shell may be formed with walls suitabl threaded to fit the lamp socket, and this shell may be then subjected to various operations, resulting in the final roduction of a lamp base similar in general appearance to the standard ty e of base now employed, but consisting of a threaded portion and a ti portion, each consisting of electrolytical y deposited conducting metal and the two se arated by insulating material.

11 carryin out my invention I preferably provide a mo (1, such as is represented in Fig. 1, comprising two split or separated portions 1 and 2, which mold is provided with a recess having the shape of the desired lamp base, and suitably dimensioned to allow for the subsequent shrinka e of metal, and the deposition of copper. mold may be of any desired material, such as metal, paper or other suitable substance, and may be constructed in any well-known and usual way, and the shape of the mold, may, of course, be varied to suit the desired requirements and conditions.

The mold having been prepared, it is then filled with some material, which, after the deposition of the copper, may be readily withdrawn or extracted. For such material, in the present instance, I have taken a fusible metal,,such as Babbitt metal having a low melting point, for example, at or about 200. Instea of fusible metal, Wax, paraffin or other like substance may be employed, or any substance may be used which is capable of ready removal. This substance when hardened forms the false or dummy base 3, havin substantially the outline of the finished amp base.

In order to provide suitable anchorage for the subsequently deposited conducting material, provision of some kind is preferably made. In the described embodiment of my invention the mold is provided near its bottom with inwardly projecting pins 4-4, and just below the threaded portions with other pins 55, so that the false base when taken out is provided with corresponding recesses. The base is then preferably dipped in or coated by some substance which will prevent the copper from clinging to it too tenaciously when it is desired to separate the same. bronze powder or graphite, which assists the metal in dropping away from the copper when it is melted. If a non-conducting substance, suchas wax or the like, is employed for the false or dummy base, it'is of course necessary to coat the base with a substance like bronze powder or graphite as a prerequisite to the electro-plating operation.

For coating the base with metal by electroplating, any suitable apparatus or process may be employed. A large number of bases may-be coated at the same time by placing them in an electrolytic bath of suitable nature in contact with the terminals of an electric circuit passing throu h the bath and conta'ming a battery or other suitable source of electro-motive force. The nature of the bath will of course depend upon the nature of the metal which it is desired to deposit. If copper, the usual bath employed is an acid solution of copper sulfate, but it will be obvious that nickel, silver or any desired metal may be utilized.

The bases are subjected to the action of the electro-plat-ing bath as long as may be necessary to secure a deposit of conducting material of sufiicient or desired thickness, and the latter, when formed, will provide a thin, tenacious skin of conducting material over the exposed portions of the false base and conforming to the irregularities in the surface of the latter. This leaves a deposit of copper which is represented by the heavy outline upon the base indicated at 6 in Fig. 4.

Having formed the shell of conducting.

metal in this fashion, the false base is withdrawn from the shell by fusing the same at a relatively low temperature, which, of course, has no effect upon the copper or other conducting material employed for the shell, which material has a relatively high fusing point. This leaves the shell of conducting material as represented in Fig. 5, the same being provided, however, with the inwardly directed anchoring points 7 7 and the other anchoring points 8-8. ith the shell formed as shown in Fig. 5, the bottom is then filled or partly filled with a plug or button 9 of the insulating material having the axial passa e 10 for the lead wire of the lamp. Such utton may consist of any desired material and be inserted in any suitable way, but preferably the same is formed of some plastic substance which can be pressed in either by hand or by machinery, if desired, and about a suitable form to leave the passage 10 and there allowed to harden.

Any desired substance may be employed for the insulating plug or button 9, such as glass, artificial stone, or the like, or any of the usual cements employed in this art, but

This substance may be, for example,

a the substance should preferably have a heat resistance (if not less than 400 in order to withstand the probable steps of the lamp manufacture. I preferably, though not necessarily, employsome substance which is plastic at a low temperature, but will harden through standing, such, for example, as a mixture of silicate of soda, sand and cement.

in order to leave separate metallic coatings to act as contacts for the lead wires the portion 11 of the mctallic shell is then removed from the truncated conical side of the insulating plug 9, leaving the finished base ready for application to the lamp, as represented at Fig. 7, the remaining end ortion 12 of the shell comprising the meta ic terminal or contact for one lead wire of the lamp and the threaded portion 13, separated from the end portion by the insulating plug 9, forming the terminal or; contact for the other lead wire.

Prior to inserting the insulating button the inner surface of the shell thereat is preferably coated with some substance, such, for example, as collodion, which will assist the copper in separating from the button when it is removed.

The metal portion 11 may be removed in any desired way and may be ground off from the insulating button or cut away by suitable machinery.

When the base is completed, as shown in Fig. 7, it will be seen that the anchors 7 effectively retain the shell portion 12 in position upon the insulating plug, while the threaded shell )ortion 13 has firm engagement with the plug by means of the anchors'8.

Instead of forming the insulating plug or button in the shell as described, a previously formed button, such as 1.4 (Fig. 2) may be placed in the bottom of the mold, which latter is shaped accurately to receive the same, and the false base is then cast on top of this button, as represented at 15, Fig. 2. Suitable interlocking surfaces 16 may be rovided between the button and the fusible metal portion of the base to cause adherence between the two.

The button 14 may be formed of able substance, such as glass, lava, bone, slate, artificial stone, porcelain, white enamel, or any other suitable insulating material, and may be given some such shape as shown whereby there is rovided the neck or groove 17 and the sma ler neck or groove 18 nearer the tip, these grooves acting eliectively to anchor the subsequently deposited metal shell thereto. the insulating button 14 attached is then electro-plated as above described, the fusible portion 15 of the base melted out and the strip of metal overlying the truncated coniany Sta This false base with cal portion 19 of the base cut or ground'away,

'- ample, as is shown in In order to diminish theamount' of fusible metal required, a core may be emp loyed in connection with the mold shown in ig. 1, so that the false base is formed in the shape of a shell instead of a solid plu Furthermore, if desired a mold, such as s own in Fig. 3, may be used where a core 20 of about thesize of the completed base is used, and a shell 21 of fusible metal formed, on the inside of which the metallic shell of conducting material is iefposited in the generaLfsshion described.

ter this conducting shell has been formed upon'the interior of the fusible metal shell, the latter is melted away as before.

In electro-plating the false base. shown in Figs. 2 and 8 it will be understood, of course, that the insulating button is coated with graphite or bronze powder before being placed in the electrolytic bath in order that the deposit of-cop er may take place upon its entire surface f desired, instead of cutting away the strip or area of metal interv'ening between the two terminal contacts of the lamp, the metal may be de osited, in the first instance, upon separate areas, if desired by omitting the coating of bronze powder or other conducting material along the portion 19 of the button, or wherever the deposit of metal is not required. The same result may be accomplished in the formin of the base shown in Figs. 1, 4, 5, 6

and 7 y coatin over the portion 11 of the base, where no eposit of copper is required,

with some insulating substance, such as wax or araflin.

e base after completion may be a plied to the lamp in any desired way, such, or ex- Fig. 9, where it is cemented thereto by a body 22 of cementitious material consisting of plaster, cement, or any other suitable substance, the lead wires bein secured to the end contacts and the threade shell portion, respectively, in the manner above described.

The lamp base as constructed by the de- I scribed process may be made economically in large quantities and with almost exact uniformit While have shown and described one form of my invention and one mode of carrying the same into effect, it is to be understood that-the same is not limited to the details of construction here described or to the exact steps of the process herein set forth, but that extensive modifications therein may be made without departing from the spirit of the invention.

Claims.

1. The process of forming an incandescent lamp base which consists in roviding asuitabl formed support of fusib e material, electro ytically depositing a coating of conducting metal thereon, and providing insulating material for separating t e end and ,side contacts of the electrol tically deposited shell.

2. The process 0 forming an incandescent lamp base which consists in.forming a false base of fusible material, and. producing through the aid of such false su port electrolytically) deposited metal she portions separated y intervening insulating material.

3. The process of forming an incandescent lamp base which consists in providing a suitable mold, placing an insulating filler in the bottom of the mold, filling the mold above the filler with a material having a low fusin point, electrolyticall depositing a coating 0 conducting materia upon the sides of the fusible material and upon the tip or base of the insulating filler, and withdrawing said fusible material by subjecting it to a temperature above its melting oint.

In testimony whereof, have signed my name to this specification, in the presence of two subscribing witnesses.

Qms. S. BRasLrN, Osoaa E. Jaoxson. 

